Numerous applications require a power driver to provide a high peak power pulse for a short period of time. One such application is the deployment of automobile airbags. The deployment of airbags is regulated by a control system supported on an integrated circuit. Power drivers fabricated on the integrated circuit provide a high peak power pulse for a short period of time to a device located in the airbag called a squib. The squib is a wire that acts as the trigger for deploying the airbag. Through providing a high peak power pulse for a short period of time to the squib, the power pulse thermally destroys the squib causing the deployment of the airbag.
Proper deployment of the automobile airbag is required for the system to protect the lives of the vehicle occupants. Proper deployment of the airbag includes full deployment of the airbag at precisely the desired time during an accident. Proper deployment requires that the power drivers provide a sufficient amount of power for a sufficient amount of time to the squib to cause its thermal destruction. Unfortunately, however, over time, through normal operation of an automobile, damage can occur to an airbag system that prevents proper deployment of the airbag. Typical points of failure in the airbag system include a damaged wiring harness, damaged electrical components, short circuits and open circuits in the system. In addition to preventing any deployment of the airbag, these system defects can also cause a premature deployment, late deployment, and inadvertent deployment of the airbag system. These types of faulty airbag deployments can result in greater injury to the vehicle occupants than if the airbag had never deployed in the first place.
One method of ensuring that a large enough power pulse is provided for a long enough period of time to destroy the squib is through over-sizing the power drivers located on the integrated circuit. Through over-sizing the power devices, it is possible to provide an excessive pulse of current for an excessive amount of time in order to ensure the proper deployment of the squib. However, this solution has a financial drawback.
Over-sizing the power drivers on the integrated circuit greatly increases the cost of the system. Over-sized power drivers consume a large amount of surface area on the integrated circuit. As a result, it is necessary to increase the size of the integrated circuit. Consequently, the material costs are greatly increased. It is highly desirable to produce an optimal power driver that provides an optimal power pulse to the squib. In this manner, it is possible to optimize the size of the power devices and correspondingly reduce the cost of the device.
When an airbag fails to deploy, or deploys improperly, it is highly desirable to determine the cause. Through determining the root cause of the failed or faulty deployment, it is possible to ensure that in the future that the airbag system functions properly and meet its safety function. In order to reconstruct the root cause of the failed or faulty deployment, it is desirable to ensure that all electrical components in the airbag system remain intact after the failure to facilitate post-failure analysis. In order to conduct a post-failure airbag system analysis, it is desirable to ensure that the integrated circuit survives the failed or faulty deployment intact.
In a both a proper and a faulty or failed airbag deployment, it is possible that the integrated circuit regulating the airbag deployment will become damaged. The high peak power pulse that is supplied by the power drivers can thermally damage or destroy the integrated circuit. As a result, it becomes more difficult, if not impossible to determine if the integrated circuit caused the failed or faulty deployment. It is therefore desirable to design an integrated circuit that has power drivers that can provide a high peak power pulse for a short period of time without thermally damaging the integrated circuit.